The goal is to study biomechanical constraints of the tongue and examine its dependence on the hard palate. The first set of studies will distinguish between acoustically and biomechanically driven tongue behaviors by mapping the 3D geometry of tongue motion in normal and deaf speech. A second set of studies will use ultrasound and electropalatography to examine tongue gestures and their tongue-palate contact patterns to define the effects of tongue-palate "bracing" on tongue shape, in a cross-linguistic study. A third study will examine tongue-palate interaction in swallowing, to eliminate linguistic effects. This project is important because although critical to speech, swallowing and breathing, the tongue as a movement system is poorly understood.